Rapid production and clearance of HIV-1 and hepatitis C virus assessed by large volume plasma apheresis

Background In chronic HIV-1 infection, dynamic equilibrium exists between v iral production and clearance. The half-life of free virions can be estimat ed by inhibiting virion production with antiretroviral agents and modelling the resulting decline in plasma HIV-1 RNA. To define HIV-1 and hepatitis C virus (HCV) dynamics, we used plasma apheresis to increase virion clearanc e temporarily while leaving Virion production unaffected. Methods Plasma virus loads were measured frequently before, during, and aft er apheresis in four HIV-1-infected patients, two of whom were also co-infe cted with HCV. Rates of virion clearance were derived by non-linear least-s quare fitting of plasma virus load to a model of Viral dynamics. Findings Virion clearance rate constants were 0.0063/min (9.1/day) to 0.025 /min (36.0/day; half-life 28-110 min) for HIV-1 and 0.0038/min (5.5/day) to 0.0069/min (9.9/day; half-life 100-182 min) for HCV. These values provided estimates of daily particle production of 9.3 log(10)-10.2 log(10) particl es for HIV-1 and 11.6 log(10)-13.0 log(10) particles for HCV. Interpretation Our findings confirm that HIV-1 and HCV are produced and cle ared extremely rapidly. New estimates for HIV-1 clearance are up to ten tim es higher than previous ones, whereas HCV clearance is similar to previous estimates.